演示如何在存储过程中调用另外一个存储过程，并获取执行的错误信息

mysql>
mysql> delimiter $$
mysql>
mysql> CREATE PROCEDURE myProc()
 -> MODIFIES SQL DATA
 -> BEGIN
 -> DECLARE l_status VARCHAR(20);
->
 -> CALL myProc1(l_status);
 -> IF l_status='Duplicate Entry' THEN
 -> SELECT CONCAT('Warning: using existing definition for location ') AS warning;
 -> END IF;
 -> END$$
Query OK, 0 rows affected (0.00 sec)

mysql>
mysql> CREATE PROCEDURE myProc1(OUT out_status VARCHAR(30))
 -> BEGIN
 -> set out_status = 'Duplicate Entry';
 -> END$$
Query OK, 0 rows affected (0.00 sec)

mysql>
mysql>
mysql> delimiter ;
mysql> call myProc();
+--------------------------------------------------+
| warning |
+--------------------------------------------------+
| Warning: using existing definition for location |
+--------------------------------------------------+
1 row in set (0.00 sec)

Query OK, 0 rows affected (0.01 sec)

mysql> drop procedure myProc;
Query OK, 0 rows affected (0.00 sec)

mysql> drop procedure myProc1;
Query OK, 0 rows affected (0.00 sec)

mysql>
mysql>